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A single layer of paper or fiberglass mesh tape is sufficient to finish flat seams and inside corners of newly hung drywall, but you need something stronger for outside corners where two pieces meet. Prefabricated plastic or metal corner beading can strengthen standard 90-degree corners, but until recently it was common to use two layers of paper tape or fiber-reinforced paper tape to finish narrow 45-degree corners. Prefab 45-degree corner beading is now available and provides a more durable corner that won't buckle or crimp. Installing it is identical to installing 90-degree beading.

1

Measure the length of the corner with a tape measure. Cut a piece of 45-degree corner beading to that length with a hacksaw.

2

Spray the edges of the wall on either side of the corner with adhesive and stick the beading in place. You can also attach the beading with 1 1/4-inch drywall screws. Drive the screws with a screw gun or drill fitted with a No. 2 phillips bit. Space them about eight inches apart and sink the heads far enough to make a slight depression in the beading.

3

Coat both edges of the beading with drywall joint compound, or mud, troweling on the mud with a 4-inch knife and using the knife to scrape it flat. Spread enough mud to cover the edges of the beading. Let it dry overnight.

4

Topcoat the edges with two more coats of mud, using a 6-inch knife for the first coat and an 8-inch knife for the second to feather the edges into the wall. Let the first coat dry before you apply the second.

5

Sand the topcoat by hand with 120-grit sandpaper when it dries.

Things You Will Need

Tape measure

Spray adhesive

1 1/4-inch drywall screws

Screw gun or drill

No. 2 Phillips bit

Drywall joint compound

4-, 6- and 8-inch drywall knives

120-grit sandpaper

Tips

When you can't find 45-degree beading, the next best option is to finish the joint with fiber-reinforced paper tape. Failing that, use a double layer of ordinary paper tape.

About the Author

Chris Deziel has a bachelor's degree in physics and a master's degree in humanities. Besides having an abiding interest in popular science, Deziel has been active in the building and home design trades since 1975. As a landscape builder, he helped establish two gardening companies.